Starlight's Edge — Susan Waggoner

Zee has given up her entire world to be with David on far-future Earth, confident that their love will overcome all obstacles. But beneath its lustrous surface and dazzling technology, New Earth is full of challenges, including the animosity of David's wealthy and powerful family.

As Zee struggles to find her place, David travels back to past Earth. Then, on a mission to Pompeii on the eve of the Vesuvius eruption, he vanishes. Zee knows he is in mortal danger, but will she be able to rescue him in time?